1. Field of the Invention
The present invention relates to an improved motor control circuit and architecture, and more particularly to a low-cost, high-performance, high-volume production motor controller for use with reaction wheel assemblies (RWAs), control moment gyroscopes (CMGs) and pointing systems on space vehicles where size, weight, radiation, and reliability play important roles.
2. Description of Previous Systems

Honeywell presently produces an analog motor control system identified as the Constellation Series, an embodiment of which, the HR14X, is described in the above-referred-to related application. The Constellation Series has met the design requirements for advanced systems such as the Teledesic series of RWAs. However, with changing satellite markets there is an ever-increasing requirement for minimal-cost, minimal-size, and high-volume production devices made without compromising quality or performance. Because of the technology limitations imposed by the analog implementation of the Constellation Series RWAs, both a digital gate array and an analog control hybrid are presently required in addition to a plurality of electronic components. This undesirably increases the size and cost of the system.
The present invention draws upon the high quality and performance of the HR14X but includes a number of design modifications that further reduce the size, weight, and cost of the controller, and allow for a more flexible implementation. For example, the control function is now located on one device, the gate array, whereas in the previous system, this function was located on two devices, referred to as the digital gate array and the analog control hybrid, each about the size of the gate array of the present invention. The present invention also introduces a calibration function to the system which, with both analog and digital command paths, allows ease of reconfiguration between various user requirements. This is desirable since there are several parameters that are unique to each embodiment of the motor controller (e.g., momentum, reaction torque, torque scale factor, wheel speed, and bus voltage). Prior to the present invention, these parameters had to be xe2x80x9cdesigned inxe2x80x9d to each embodiment. In the present invention, with the introduction of the calibration function, only the calibration table needs be changed to account for the parameter changes.
In the present invention, production is improved by a less complex implementation that can be assembled faster and with improved quality and a more radiation tolerant implementation can be realized due to the elimination of critical analog components. More particularly, the present invention uses full digital circuits that require far fewer parts than an analogue design resulting in reduced size and cost. Specifically, the improved motor control circuit provides an approximate a 20% saving in size and a 10% savings in weight.